NEWTOWN, Conn. (CBS) – For the first time, a rescuer who arrived at Sandy Hook Elementary is describing his horrific experience after the Newtown shooting, and the terrible realization that there would be no survivors.

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Adam Lanza murdered 20 children and six adults at the Connecticut school. Newtown Assistant Fire Chief Ray Corbo describes the pain of setting up a triage area, only to find there were only a couple of victims to help.

“There was nobody to treat,” says Corbo. “One or two early on and then, the whole triage unit that was expecting to get multiple victims, never, we didn’t get any.”

Corbo, himself the father of a 7-year-old, remembers the parents’ anguish as they arrived after Friday’s shooting.

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“As they would get their child, they would leave,” says Corbo, “and you knew there was a certain amount of kids inside there that weren’t going to be coming out on their own power and those were the parents that were waiting, and they never came.”

What would he say to them now?

“I don’t have any words I don’t know,” he says. “I’m sorry that we couldn’t help more.”

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Corbo moved from Sandy Hook a year ago and hasn’t told his son what happened, because he says a 7-year-old shouldn’t have to hear that. His son would have been a first grader at the school if they did not move.

Christina Hager